I thought it would be best to put this where it would be easy to find
for searchers.
package com.crackwillow.filter;
import java.io.IOException;
import java.io.PrintStream;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import com.crackwillow.constant.SiteConstant;
import com.crackwillow.log.StdOut;
public class SessionExpireFilter
implements Filter {
private static final String REDIRECT = "redirect";
private static final String HTTP = "http";
private static boolean no_init = true;
private FilterConfig filterConfig;
private String redirect;
public SessionExpireFilter()
{
redirect = null;
}
public void init(FilterConfig filterConfig)
throws ServletException {
filterConfig = filterConfig;
no_init = false;
initRoute();
}
public void destroy() {
filterConfig = null;
}
public FilterConfig getFilterConfig() {
return filterConfig;
}
public void setFilterConfig(FilterConfig filterConfig) {
if(no_init) {
filterConfig = filterConfig;
initRoute();
no_init = false;
}
}
public void doFilter(ServletRequest request,
ServletResponse response,
FilterChain filterChain)
throws IOException,
ServletException {
HttpServletRequest httpRequest = (HttpServletRequest)request;
HttpSession httpSession = httpRequest.getSession(false);
if(httpSession == null ||
httpRequest.getRequestedSessionId() == null ||
redirect == null) {
filterChain.doFilter(request, response);
} else {
String sessionId = httpSession.getId();
if(sessionId.equals(httpRequest.getRequestedSessionId())) {
filterChain.doFilter(request, response);
} else {
HttpServletResponse httpResponse = (HttpServletResponse)response;
ServletContext servletContext = filterConfig.getServletContext();
if(getRedirect(redirect)) {
httpResponse.sendRedirect(redirect);
} else {
RequestDispatcher requestDispatcher =
servletContext.getRequestDispatcher(redirect);
requestDispatcher.forward(request, response);
}
}
}
}
public void initRoute() {
ServletContext servletContext = filterConfig.getServletContext();
redirect = filterConfig.getInitParameter(REDIRECT);
if(redirect == null) {
StdOut.log(SiteConstant.ERROR_LOG,"The variable redirect in
SessionExpireFilter is not set.");
}
}
private boolean getRedirect(String redirectURL) {
int i = redirectURL.indexOf(":");
if(i <= 0) {
return false;
} else {
return redirectURL.substring(0,
i).toUpperCase().toLowerCase().startsWith(HTTP);
}
}
}
/*
<filter>
<filter-name>SessionExpireFilter</filter-name>
<filter-class>com.crackwillow.filter.SessionExpireFilter</filter-class>
<init-param>
<param-name>redirect</param-name>
<param-value>/index.jsp</param-value>
</init-param>
</filter>
c) describe a mapping for this filter in web.xml. E.g.:
<filter-mapping>
<filter-name>SessionExpireFilter</filter-name>
<url-pattern>*.jsp</url-pattern>
</filter-mapping>
*/
Jack
--
------------------------------
"You can lead a horse to water but you cannot make it float on its back."
~Dakota Jack~
"You can't wake a person who is pretending to be asleep."
~Native Proverb~
"Each man is good in His sight. It is not necessary for eagles to be crows."
~Hunkesni (Sitting Bull), Hunkpapa Sioux~
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